# `StatifierBlocks.Core.ResumableGroup`
[🔗](https://github.com/riddler/statifier_blocks/blob/v0.44.1/lib/statifier_blocks/core/resumable_group.ex#L1)

`core.resumable_group`: a group whose `config` carries a history mode
(ADR-0002 decision 10).

The same two slots as `StatifierBlocks.Core.Group` - `body` and
`interrupts` - plus one `:select` field deciding what re-entering the
group after an interrupt returns to:

| `history` | Means |
|---|---|
| `"shallow"` | re-enter at the top-level step the group was last in |
| `"deep"` | re-enter at the exact position, however deeply nested |

The mode is *only* config. ADR-0005 decision 10 is explicit that it needs
no editor support whatsoever: it renders through the ordinary form
machinery like any other `:select`, and the presentation metadata this
type carries is about its two slots, not about resuming.

`history` is required rather than defaulted-when-absent. The schema
declares a default of `"shallow"`, so the editor fills it in on insert,
and a stored document missing it is a finding an author can see and fix -
which is the outcome a silent default would hide, on the one field whose
value changes where a workflow resumes.

# `emit`

`StatifierBlocks.Core.Group`'s shape plus a `<history>` inside the body
region, of the type `history` names. A `"resume"` handler targets that
history rather than the `<parallel>`, so the body re-enters where it left
off instead of restarting - which is the whole of what this config buys,
and why ADR-0002 decision 10 could leave it as one `:select` field.

A config carrying neither `"shallow"` nor `"deep"` is refused here as
well as in `validate_config/1`. The compiler runs the Config stage first,
so that arm is unreachable through `StatifierBlocks.Compiler`; it exists
because `emit/2` is a total function of its arguments and has to answer
for the config it was handed rather than for the one it assumed.

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*Consult [api-reference.md](api-reference.md) for complete listing*